Faculty Opinions recommendation of The C. elegans touch response facilitates escape from predacious fungi.

AbstractTouch deforms, or strains, the skin beyond the immediate point of contact. The spatiotemporal nature of the touch-induced strain fields depend on the mechanical properties of the skin and the tissues below. Somatosensory neurons that sense touch branch out within the skin and rely on a set of mechano-electrical transduction channels distributed within their dendrites to detect mechanical stimuli. Here, we sought to understand how tissue mechanics shape touch-induced mechanical strain across the skin over time and how individual channels located in different regions of the strain field contribute to the overall touch response. We leveraged C. elegans’ touch receptor neurons (TRNs) as a simple model amenable to in vivo whole-cell patch clamp recording and an integrated experimental-computational approach to dissect the mechanisms underlying the spatial and temporal dynamics that we observed. Consistent with the idea that strain is produced at a distance, we show that delivering strong stimuli outside the anatomical extent of the neuron is sufficient to evoke MRCs. The amplitude and kinetics of the MRCs depended on both stimulus displacement and speed. Finally, we found that the main factor responsible for touch sensitivity is the recruitment of progressively more distant channels by stronger stimuli, rather than modulation of channel open probability. This principle may generalize to somatosensory neurons with more complex morphologies.SummaryThrough experiment and simulation, Katta et al. reveal that pushing faster and deeper recruits more and more distant mechano-electrical transduction channels during touch. The net result is a dynamic receptive field whose size and shape depends on tissue mechanics, stimulus parameters, and channel distribution within sensory neurons.

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Investigating the Roles of RNA Binding Protein Combinations in Neuronal Function and Organismal Behavior

10.25172/jour.4.1.7 ◽

2019 ◽

Vol 4 (Spring 2019) ◽

Author(s):

Alexa Vandenburg

Keyword(s):

Binding Sites ◽

Neuronal Development ◽

Rna Binding ◽

Rna Binding Proteins ◽

Binding Protein ◽

Rna Binding Protein ◽

Wild Type ◽

C Elegans ◽

Neuronal Gene ◽

Touch Response

The Norris lab recently identified two RNA binding proteins required for proper neuron-specific splicing. The lab conducted touch- response behavioral assays to assess the function of these proteins in touch-sensing neurons. After isolating C. elegans worms with specific phenotypes, the lab used automated computer tracking and video analysis to record the worms’ behavior. The behavior of mutant worms differed from that of wild-type worms. The Norris lab also discovered two possible RNA binding protein sites in SAD-1, a neuronal gene implicated in the neuronal development of C. elegans1. These two binding sites may control the splicing of SAD-1. The lab transferred mutated DNA into the genome of wild-type worms by injecting a mutated plasmid. The newly transformed worms fluoresced green, indicating that the two binding sites control SAD-1 splicing.

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A dynamic body model of the nematode C. elegans with a touch-response circuit

2005 IEEE International Conference on Robotics and Biomimetics - ROBIO ◽

10.1109/robio.2005.246325 ◽

2005 ◽

Cited By ~ 10

Author(s):

M. Suzuki ◽

T. Tsuji ◽

H. Ohtake

Keyword(s):

C Elegans ◽

Body Model ◽

Touch Response

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Precise optical control of gene expression in C. elegans using improved genetic code expansion and Cre recombinase

eLife ◽

10.7554/elife.67075 ◽

2021 ◽

Vol 10 ◽

Author(s):

Lloyd Davis ◽

Inja Radman ◽

Angeliki Goutou ◽

Ailish Tynan ◽

Kieran Baxter ◽

...

Keyword(s):

Gene Expression ◽

Genetic Code ◽

Cre Recombinase ◽

Symmetric Pair ◽

Control Of Gene Expression ◽

C Elegans ◽

Individual Contributions ◽

Touch Response ◽

Genetic Code Expansion ◽

The Individual

Synthetic strategies for optically controlling gene expression may enable the precise spatiotemporal control of genes in any combination of cells that cannot be targeted with specific promoters. We develop an improved genetic code expansion system in C. elegans and use it to create a photo-activatable Cre recombinase. We laser-activate Cre in single neurons within a bilaterally symmetric pair to selectively switch on expression of a loxP controlled optogenetic channel in the targeted neuron. We use the system to dissect, in freely moving animals, the individual contributions of the mechanosensory neurons PLML/PLMR to the C. elegans touch response circuit, revealing distinct and synergistic roles for these neurons. We thus demonstrate how genetic code expansion and optical targeting can be combined to break the symmetry of neuron pairs and dissect behavioural outputs of individual neurons that cannot be genetically targeted.

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Synthetic ablations in the C. elegans nervous system

Network Neuroscience ◽

10.1162/netn_a_00115 ◽

2020 ◽

Vol 4 (1) ◽

pp. 200-216 ◽

Cited By ~ 1

Author(s):

Emma K. Towlson ◽

Albert-László Barabási

Keyword(s):

Nervous System ◽

Synthetic Lethality ◽

Neural System ◽

Network Control ◽

Loss Of Control ◽

C Elegans ◽

Touch Response ◽

Systematic Framework ◽

Systematic Knowledge

Synthetic lethality, the finding that the simultaneous knockout of two or more individually nonessential genes leads to cell or organism death, has offered a systematic framework to explore cellular function, and also offered therapeutic applications. Yet the concept lacks its parallel in neuroscience—a systematic knowledge base on the role of double or higher order ablations in the functioning of a neural system. Here, we use the framework of network control to systematically predict the effects of ablating neuron pairs and triplets on the gentle touch response. We find that surprisingly small sets of 58 pairs and 46 triplets can reduce muscle controllability in this context, and that these sets are localized in the nervous system in distinct groups. Further, they lead to highly specific experimentally testable predictions about mechanisms of loss of control, and which muscle cells are expected to experience this loss.

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Comparing Caenorhabditis elegans gentle and harsh touch response behavior using a multiplexed hydraulic microfluidic device

10.1101/162990 ◽

2017 ◽

Author(s):

Patrick D. McClanahan ◽

Joyce H. Xu ◽

Christopher Fang-Yen

Keyword(s):

Caenorhabditis Elegans ◽

Microfluidic Device ◽

Receptive Fields ◽

The Body ◽

Mechanical Stimuli ◽

C Elegans ◽

Response Characteristics ◽

Touch Receptor Neurons ◽

Touch Response ◽

Receptor Neurons

AbstractThe roundworm Caenorhabditis elegans is an important model system for understanding the genetics and physiology of touch. Classical assays for C. elegans touch, which involve manually touching the animal with a probe and observing its response, are limited by their low throughput and qualitative nature. We developed a microfluidic device in which several dozen animals are subject to spatially localized mechanical stimuli with variable amplitude. The device contains 64 sinusoidal channels through which worms crawl, and hydraulic valves that deliver touch stimuli to the worms. We used this assay to characterize the behavioral responses to gentle touch stimuli and the less well studied harsh (nociceptive) touch stimuli. First, we measured the relative response thresholds of gentle and harsh touch. Next, we quantified differences in the receptive fields between wild type worms and a mutant with non-functioning posterior touch receptor neurons. We showed that under gentle touch the receptive field of the anterior touch receptor neurons extends into the posterior half of the body. Finally, we found that the behavioral response to gentle touch does not depend on the locomotion of the animal immediately prior to the stimulus, but does depend on the location of the previous touch. Responses to harsh touch, on the other hand, did not depend on either previous velocity or stimulus location. Differences in gentle and harsh touch response characteristics may reflect the different innervation of the respective mechanosensory cells. Our assay will facilitate studies of mechanosensation, sensory adaptation, and nociception.

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Caenorhabditis elegans exhibits positive gravitaxis

BMC Biology ◽

10.1186/s12915-021-01119-9 ◽

2021 ◽

Vol 19 (1) ◽

Author(s):

Wei-Long Chen ◽

Hungtang Ko ◽

Han-Sheng Chuang ◽

David M. Raizen ◽

Haim H. Bau

Keyword(s):

Caenorhabditis Elegans ◽

Molecular Mechanisms ◽

Life Forms ◽

The Body ◽

C Elegans ◽

Neural Processes ◽

Sensory Cilia ◽

Touch Response ◽

Vector Direction ◽

Hydrodynamic Effects

Abstract Background Gravity plays an important role in most life forms on Earth. Yet, a complete molecular understanding of sensing and responding to gravity is lacking. While there are anatomical differences among animals, there is a remarkable conservation across phylogeny at the molecular level. Caenorhabditis elegans is suitable for gene discovery approaches that may help identify molecular mechanisms of gravity sensing. It is unknown whether C. elegans can sense the direction of gravity. Results In aqueous solutions, motile C. elegans nematodes align their swimming direction with the gravity vector direction while immobile worms do not. The worms orient downward regardless of whether they are suspended in a solution less dense (downward sedimentation) or denser (upward sedimentation) than themselves. Gravitaxis is minimally affected by the animals’ gait but requires sensory cilia and dopamine neurotransmission, as well as motility; it does not require genes that function in the body touch response. Conclusions Gravitaxis is not mediated by passive forces such as non-uniform mass distribution or hydrodynamic effects. Rather, it is mediated by active neural processes that involve sensory cilia and dopamine. C. elegans provides a genetically tractable system to study molecular and neural mechanisms of gravity sensing.

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Optically splitting symmetric neuron pairs in C. elegans

10.1101/2020.05.02.072363 ◽

2020 ◽

Author(s):

Lloyd Davis ◽

Inja Radman ◽

Angeliki Goutou ◽

Ailish Tynan ◽

Kieran Baxter ◽

...

Keyword(s):

Genetic Code ◽

Single Cell ◽

Symmetric Pair ◽

C Elegans ◽

Large Numbers ◽

Individual Contributions ◽

Touch Response ◽

Expansion System ◽

Genetic Code Expansion ◽

The Individual

AbstractTwo thirds of the 302 neurons in C. elegans form bilaterally symmetric pairs in its physical connectome, and similar gross morphological symmetries are seen in the nervous systems of many other animals. A central question is whether and how this morphological symmetry is broken to produce functional asymmetry. Addressing this question, in all but two cases, has been impossible because no promoters are known that can direct gene expression to a single cell within a symmetric pair. Here we develop an efficient genetic code expansion system in C. elegans and use this system to create a photo-activatable version of Cre recombinase. Using this system, we target single neurons within a bilaterally symmetric pair (PLMR and PLML) with a laser. This turns on Cre and thereby switches on expression of an optogenetic channel in a single cell. We hereby overcome the limitation that these neurons cannot be targeted by genetic means. Our approach enables the generation of large numbers of animals for downstream experiments. By globally illuminating groups of freely moving animals to stimulate the targeted neurons that express an optogenetic channel we dissect the individual contributions of PLMR and PLML to the C. elegans touch response. Our results reveal that the individual neurons make asymmetric contributions to this behaviour, and suggest distinct roles for PLMR and PLML in the habituation to repeated stimulation. Our results demonstrate how genetic code expansion and optical targeting can be combined to break the symmetry of neuron pairs in C. elegans and thereby dissect the contributions of individual neurons to behaviour.

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Regulated distribution of mitochondria in touch receptor neurons of C. elegans influences touch response

10.1101/2020.07.26.221523 ◽

2020 ◽

Author(s):

Anjali Awasthi ◽

Souvik Modi ◽

Sneha Hegde ◽

Anusheela Chatterjee ◽

Sudip Mondal ◽

...

Keyword(s):

Molecular Motors ◽

Neuronal Function ◽

Mitochondrial Density ◽

Neuronal Process ◽

C Elegans ◽

Touch Receptor Neurons ◽

Touch Response ◽

Receptor Neurons ◽

Touch Receptor Neuron

AbstractDensity of mitochondria and their localization at specific sub-cellular regions of the neurons is regulated by molecular motors, their adaptors and the cytoskeleton. However, the regulation of the mitochondrial density, the positioning of mitochondria along the neuronal process and the role of axonal mitochondria in neuronal function remain poorly understood. This study shows that the density of mitochondria in C. elegans touch receptor neuron processes remains constant through development. Simulations show that mitochondrial positioning along parts of the neuronal process that are devoid of synapses is regulated. Additionally, we also demonstrate that axonal mitochondria are necessary for maintaining touch responsiveness.

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